Backlights of liquid crystal displays are equipped with a brightness enhancement sheet, such as a prism sheet or a microlens sheet, for improving brightness. The brightness-improving effect of brightness enhancement sheets increases with the refractive index. Thus, resin materials having a molecular structure with a higher refractive index are being developed, and the addition of inorganic fine particles to increase the refractive index is being investigated.
For example, Patent Literature 1 describes a curable composition containing zirconium oxide fine particles and phenoxyethyl acrylate. Cured products of such resin compositions containing inorganic fine particles have high refractive indexes but are easily scratched due to low elasticity.